Disclosed in U.S. Patent Application Publication No. 2009/0145504 is a fuel injector rail assembly for direct injection of fuel under high pressure, which comprises an elongate fuel distribution tube formed therein with a fuel passage to be supplied with pressurized fuel from a fuel pump, four fuel injector sockets each formed to contain therein a fuel injection valve in a fluid-tight manner and being integrally secured to the fuel distribution tube, and four cylindrical bosses each formed with a hole for mounting the fuel distribution tube on an engine head by means of a bolt and being integrally secured to the fuel distribution tube. Because in the fuel injector rail assembly, the fuel injector sockets each are applied with a reaction force from the fuel injection valves inserted into each cylinder of the engine when fuel is directly injected into the cylinder, the mounting bosses are secured to the fuel distribution tube at a position adjacent the respective injector sockets to retain them in place.
The mounting bosses in the form of machined component parts are expensive to manufacture. Because the fuel injector sockets and the mounting bosses are respectively assembled to the fuel distribution tube, it is difficult to enhance precision of alignment of the component parts. It is, therefore, a primary object of the present invention to restrain the manufacturing cost of the fuel injector rail assembly. It is a further object of the present invention to enable precise alignment of the component parts of the fuel injector rail assembly in a simple manner.